Board of Trustees - Narrative (Details)	May 23, 2014 trustee
Board of Trustees
Number of individuals elected to serve on Board of Trustees	7eqc_NumberOfTrusteesInBoardOfTrustees

Represents the number of trustees serving in the board of trustees of the reporting entity.

No definition available.

Name:	eqc_NumberOfTrusteesInBoardOfTrustees
Namespace Prefix:	eqc_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant